System for peritoneal dialysis

ABSTRACT

A system for dialysis is disclosed. An example peritoneal dialysis system includes a peritoneal dialysis machine including a pumping mechanism, and a sensor configured to measure a property of peritoneal dialysis fluid. The peritoneal dialysis system also includes a disposable cassette operable with the peritoneal dialysis machine. The disposable cassette includes a fluid source inlet for accepting fluid from a fluid source and a fluid flow path in fluid communication with the fluid source inlet. The fluid flow path includes a pump chamber operable with the pumping mechanism to pump fluid through the fluid flow path. The disposable cassette also includes a concentrate inlet for fluidly communicating concentrate to the fluid flow path, and a sensor chamber located along the fluid flow path and operable with the sensor. The sensor is configured to provide feedback to the peritoneal dialysis machine for mixing the concentrate for forming peritoneal dialysis fluid.

PRIORITY CLAIM

This application claims priority to and the benefit as a continuation ofU.S. patent application Ser. No. 15/905,944, filed Feb. 27, 2018,entitled “Disposable Set and System for Dialysis”, which is a divisionalof U.S. patent application Ser. No. 15/809,628, filed Nov. 10, 2017,entitled “Disposable Cassette and System for Dialysis”, now U.S. Pat.No. 10,179,200, issued January 15, which is a continuation of U.S.patent application Ser. No. 14/094,306, filed Dec. 2, 2013, entitled“Weight-Controlled Sorbent System For Hemodialysis”, now U.S. Pat. No.9,814,820, issued Nov. 14, 2017, which is a continuation of U.S. patentapplication Ser. No. 13/213,707, filed Aug. 19, 2011, entitled“Weight/Sensor-Controlled Sorbent System For Hemodialysis”, now U.S.Pat. No. 8,597,227, issued Dec. 3, 2013, which is a continuation of U.S.patent application Ser. No. 12/562,730, filed Sep. 18, 2009, entitled“Systems And Methods For Performing Peritoneal Dialysis”, now U.S. Pat.No. 8,357,113, issued Jan. 22, 2013, which is a continuation of U.S.patent application Ser. No. 10/623,316, filed Jul. 17, 2003, entitled“Systems And Methods For Performing Peritoneal Dialysis”, now U.S. Pat.No. 7,867,214, issued Jan. 11, 2011, which claims priority to and thebenefit of U.S. Provisional Patent Application Ser. No. 60/397,131,filed Jul. 19, 2002, entitled “Systems And Methods For PerformingPeritoneal Dialysis”, the entire contents of each of which are herebyincorporated by reference and relied upon.

BACKGROUND

The present invention generally relates to dialysis systems. Morespecifically, the present invention relates to regeneration dialysissystems and continuous flow dialysis systems. The present invention alsorelates to methods of performing dialysis therapies.

Due to disease, insult or other causes, a person's renal system canfail. In renal failure of any cause, there are several physiologicalderangements. The balance of water, minerals and the excretion of dailymetabolic load is no longer possible in renal failure. During renalfailure, toxic end products of nitrogen metabolism (urea, creatinine,uric acid, and others) can accumulate in blood and tissues.

Kidney failure and reduced kidney function have been treated withdialysis. Dialysis removes waste, toxins and excess water from the bodythat would otherwise have been removed by normal functioning kidneys.Dialysis treatment for replacement of kidney functions is critical tomany people because the treatment is life saving. One who has failedkidneys could not continue to live without replacing at least thefiltration functions of the kidneys.

Hemodialysis and peritoneal dialysis are two types of dialysis therapiescommonly used to treat loss of kidney function. Hemodialysis treatmentutilizes the patient's blood to remove waste, toxins and excess waterfrom the patient. The patient is connected to a hemodialysis machine andthe patient's blood is pumped through the machine. Catheters areinserted into the patient's veins and arteries to connect the blood flowto and from the hemodialysis machine. As blood passes through a dialyzerin the hemodialysis machine, the dialyzer removes the waste, toxins andexcess water from the patient's blood and returns the blood to infuseback into the patient. A large amount of dialysate, for example about120 liters, is used to dialyze the blood during a single hemodialysistherapy. The spent dialysate is then discarded. Hemodialysis treatmentlasts several hours and is generally performed in a treatment centerabout three or four times per week.

One type of hemodialysis therapy is regenerative hemodialysis. Thistherapy uses a hemodialysis system, which includes a cartridge fordialysate regeneration. One such cartridge is manufactured under thename REDY™ by Sorb Technology, Oklahoma City, Okla. In this system, thedialysate fluid flow path must be properly cleaned before thehemodialysis machine can be used on another patient. Also, the dialysatefluid flow path is not a closed system, i.e., the dialysate fluid flowpath is open to the atmosphere, such that oxygen from the atmosphere cancontact fluid in the system and foster the growth of bacteria in same.Consequently, contamination of such a dialysis system can be a concern.Further, the dialysate fluid exiting the REDY™ cartridge is not suitablefor peritoneal dialysis because the fluid is relatively acidic and not,therefore, physiologic. Moreover, this system requires the attention ofmedical personnel during therapy.

Peritoneal dialysis utilizes a sterile, pyrogen free dialysis solutionor “dialysate”, which is infused into a patient's peritoneal cavity. Thedialysate contacts the patient's peritoneal membrane in the peritonealcavity. Waste, toxins and excess water pass from the patient'sbloodstream through the peritoneal membrane and into the dialysate. Thetransfer of waste, toxins, and water from the bloodstream into thedialysate occurs due to diffusion and osmosis, i.e., an osmotic gradientoccurs across the membrane. The spent dialysate drains from thepatient's peritoneal cavity and removes the waste, toxins and excesswater from the patient. This cycle is repeated on a semi-continuous orcontinuous basis.

There are various types of peritoneal dialysis therapies, includingcontinuous ambulatory peritoneal dialysis (“CAPD”) and automatedperitoneal dialysis. CAPD is a manual dialysis treatment, in which thepatient connects an implanted catheter to a drain and allows a spentdialysate fluid to drain from the peritoneal cavity. The patient thenconnects the catheter to a bag of fresh dialysate and manually infusesfresh dialysate through the catheter and into the patient's peritonealcavity. The patient disconnects the catheter from the fresh dialysatebag and allows the dialysate to dwell within the cavity to transferwaste, toxins and excess water from the patient's bloodstream to thedialysate solution. After a dwell period, the patient repeats the manualdialysis procedure.

In CAPD the patient performs several drain, fill, and dwell cyclesduring the day, for example, about four times per day. Each exchange ortreatment cycle, which includes a drain, fill and dwell, takes aboutfour hours. Manual peritoneal dialysis performed by the patient requiresa significant amount of time and effort from the patient. Thisinconvenient procedure leaves ample room for improvement and therapyenhancements to improve patient quality of life.

Automated peritoneal dialysis is similar to continuous peritonealdialysis in that the dialysis treatment includes a drain, fill, anddwell cycle. However, a dialysis machine automatically performs three tofour cycles of peritoneal dialysis treatment, typically overnight whilethe patient sleeps.

With automated peritoneal dialysis, an automated dialysis machinefluidly connects to an implanted catheter. The automated dialysismachine also fluidly connects to a source or bag of fresh dialysate andto a fluid drain. The dialysis machine pumps spent dialysate from theperitoneal cavity, though the catheter, to the drain. The dialysismachine then pumps fresh dialysate from the dialysate source, throughthe catheter, and into the patient's peritoneal cavity. The automatedmachine allows the dialysate to dwell within the cavity so that thetransfer of waste, toxins and excess water from the patient'sbloodstream to the dialysate solution can take place. A computercontrols the automated dialysis machine so that the dialysis treatmentoccurs automatically when the patient is connected to the dialysismachine, for example, when the patient sleeps. That is, the dialysissystem automatically and sequentially pumps fluid into the peritonealcavity, allows for dwell, pumps fluid out of the peritoneal cavity, andrepeats the procedure.

Several drain, fill, and dwell cycles will occur during the treatment.Also, a “last fill” is often used at the end of the automated dialysistreatment, which remains in the peritoneal cavity of the patient whenthe patient disconnects from the dialysis machine for the day. Automatedperitoneal dialysis frees the patient from having to manually performingthe drain, dwell, and fill steps. Automated dialysis can improve thepatient's dialysis treatment and undoubtedly improves the patient'squality of life.

So-called “continuous flow” peritoneal dialysis (“CFPD”) systems thatpurport to provide continuous dialysate flow exist. However, thesesystems typically have a single pass fluid flow. That is, the dialysateflows into, through, and out of the peritoneal cavity one time beforebeing sent to a drain. The “spent” dialysate (waste laden dialysate)from the patient collects in a drain bag, which is discarded, or runsinto a household drain or other drain. Known CFPD systems, therefore,typically use a volume of dialysate one time and then discard it. Thatis, the systems have no ability to regenerate or reuse a quantity ofdialysate.

The effectiveness of existing peritoneal dialysis therapies, andexisting systems which perform the therapies, depends upon the amount ofdialysis fluid used. For example, typical peritoneal dialysis therapyrequires about 4 to 6 exchanges of dialysate (drain, fill, dwell) withabout 2 to 3 liters of dialysate for each exchange. Peritoneal dialysisis a daily therapy performed 7 days per week. As a consequence, 240 to540 liters of fresh dialysate must be delivered to and stored at apatient's home each month. Increasing dialysate dosage to increasetherapy effectiveness will necessitate even more dialysate.

Therefore, needs exist to provide improved dialysis systems and methodsof performing dialysis. Particularly, needs exist to provide closed loopperitoneal dialysis systems and methods that regenerate or reuse spentdialysate. There are needs for such systems and methods to be compatiblewith CFPD treatment so that patients can perform the procedure at homewithout the need for storing an inordinate amount of fresh dialysatebags. There are further needs for such systems and methods to beautomated so that the procedure can be largely performed at night whilethe patient sleeps.

SUMMARY

Generally, the present invention provides improved dialysis systems andimproved methods of performing dialysis. More particularly, the presentinvention provides systems and methods for continuous flow dialysis(“CFD”) and regenerative dialysis, and in combination, continuous flowregenerative dialysis (“CFRD”). This invention also includes improvedsystems and methods for performing hemodialysis.

The dialysis system of the present invention automatically performsdialysis therapy on a patient, for example, during nighttime while thepatient sleeps. The present invention automatically regenerates spentdialysate into fresh dialysate that is reintroduced into the patient tobe used again for dialysis treatment. Further, the dialysis systemprovides continuous fluid flow simultaneously to and from the patient.

To this end, in one embodiment of the present invention a system forproviding dialysis is provided. The system includes a patient fluid loophaving a first pump and multiple patient lumens. The system includes asecond fluid loop including a second pump and a medical fluidregenerator. A membrane device is placed in fluid contact with andseparates the patient and the second fluid loops. The membrane deviceallows at least one selected component of the fluid in the patient fluidloop to transfer to the second fluid loop. The second loop is otherwiseclosed except for the transfer of the selected component via themembrane device. A controller is also provided that operates the firstand second pumps to recirculate fluid in the patient loop and the secondloop.

The system is adaptable to be used with various different types ofcomponents and to be arranged in a variety of ways.

For example, in an embodiment, the membrane device is a dialyzer.

In an embodiment, a pressure gradient exists across the membrane device.

In an embodiment, the patient loop is also closed except for thetransfer of the selected component via the membrane device and theventing of air/gas.

In an embodiment, the membrane device includes a nanofilter which allowsurea to pass from the patient fluid loop to the second fluid loop.

In an embodiment, the medical fluid regenerator includes a uremic toxinsorbent.

In an embodiment, the medical fluid regenerator can include any or allof the following materials: urease, zirconium phosphate, zirconiumoxide, and carbon.

In an embodiment, the system includes a gas separator that removes gasfrom one or both of the patient and second fluid loops.

In an embodiment, the gas separator and the medical fluid regeneratorare provided in a single device.

In an embodiment, the system includes a gas vent that vents gases fromthe patient and second fluid loops.

In an embodiment, the second fluid loop includes a multi-analyte sensorthat monitors a concentration of electrolytes in the medical fluid.

In an embodiment, peritoneal dialysis fluid is circulated through thepatient fluid loop.

In an embodiment, blood is circulated through the patient fluid loop.

In an embodiment, at least parts of the patient fluid loop and thesecond fluid loop are provided in a disposable device.

In an embodiment, the second fluid loop includes a balance chamber thatbalances flow within the second fluid loop.

In an embodiment, the controller enables fluid to flow in oppositedirections through the multiple patient.

In an embodiment, the system includes a dual lumen catheter that definesthe multiple patient lumens.

In an embodiment, one or both of the patient fluid loop and the secondfluid loop includes an in-line fluid heater.

In an embodiment, the in-line fluid heater includes a radiant heater anda plate heater.

In an embodiment, the system includes a medical fluid sensor whichsenses one or more indicators including: ammonia, ammonium and pH.

In an embodiment, the system includes a fluid volume sensor in or bothof the patient and second fluid loops.

In an embodiment, the fluid volume sensor includes a capacitance fluidvolume sensor that uses a chamber in fluid communication with one orboth of the fluid loops.

In an embodiment, the chamber is a pump chamber.

In an embodiment, the system includes an ultrafiltrate container influid communication with at least one of the patient and second fluidloops.

In an embodiment, the system includes a fluid concentrate container influid communication with one or both of the patient and second fluidloops.

The system as described herein uses, in one embodiment, a disposabledialysis cassette. The cassette includes a flexible membrane covering apatient pump chamber and a regeneration pump chamber. The cassetteincludes an apparatus for fluidly connecting the patient pump chamber toa closed loop patient fluid path. The cassette further includes anapparatus for fluidly connecting the regeneration pump chamber to aclosed loop regeneration fluid path. The patient path and theregeneration path each fluidly communicates with a dialyzer.

The cassette is adaptable to be used with various different types ofcomponents and to be arranged in a variety of ways.

For example, in an embodiment, the disposable cassette defines a fluidpath leading to a port that fluidly communicates with a dialysatesorbent cartridge.

In an embodiment, the disposable cassette defines a fluid path leadingto a port that fluidly communicates with a gas separator.

In an embodiment, the disposable cassette defines a fluid path leadingto a port that fluidly communicates with a dialysis concentratecontainer.

In an embodiment, the disposable cassette defines a fluid path leadingto a port that fluidly communicates with a dialysate last bag.

In an embodiment, the disposable cassette defines a fluid path leadingto a port that fluidly communicates with a dialysate bag.

In an embodiment, the disposable cassette defines a fluid path leadingto a port that fluidly communicates with a drain container.

In an embodiment, the disposable cassette defines a fluid path leadingto a port that fluidly communicates with a patient fluid connector.

Further, the disposable cassette can define a fluid path for atwenty-four hour collection and/or a remote analyte sensor.

The disposable cassette operates with a dialysis therapy device. Thetherapy device includes a housing having a portion that receives thedisposable cassette. The housing houses a patient pump actuator thatpumps fluid through a patient path defined at least in part by thedisposable cassette. The housing also houses a regeneration pumpactuator that pumps fluid through a regeneration path defined at leastin part by the disposable cassette.

The dialysis therapy device is also adaptable to be used with variousdifferent types of components and to be arranged in a variety of ways.

For example, in an embodiment, the dialysis therapy device includes atleast one fluid volume measurement sensor component that cooperates withthe patient pump actuator and the regeneration pump actuator.

In an embodiment, the housing houses a fluid heater.

In an embodiment, the housing houses at least one sensor, such as anammonia sensor, an ammonium sensor and a pH sensor.

In an embodiment, the housing houses at least one valve actuator thatoperates with the disposable cassette.

The present invention includes a plurality of different methods foroperating the systems and apparatuses described herein. In oneembodiment, a method is provided for moving fluid in a dialysis system.The method includes continuously recirculating a first fluid through apatient loop. The method includes continuously recirculating a secondfluid through a regeneration loop. At least one waste component issimultaneously transferred from the patient loop to the regenerationloop through a device shared by both loops. The loops are otherwiseclosed except for the fluid transfer through the device. The method alsoincludes removing the at least one waste component from the regenerationloop.

The first and second fluids can both include dialysate. Alternatively,the first fluid includes blood and the second fluid includes dialysate.

In an embodiment, the method includes flowing the second fluid in theregeneration loop through a waste sorbent and absorbing at least some ofthe waste component.

In an embodiment, the method includes the step of heating the at leastone of the first and second fluids.

In an embodiment, the method includes the step of removing ultrafiltratefrom at least one of the first and second fluids.

In an embodiment, the method includes the step of adding dialysate to atleast one of the first and second fluids.

In an embodiment, the method includes the step of adding concentrate toat least one of the first and second fluids.

In an embodiment, the method includes the step of removing gas from atleast one of the first and second fluids.

In an embodiment, the method includes the step of balancing the flow offluid in at least one of the patient loop and the regeneration loop.

In an embodiment, the method includes the step of sensing a volume offlow of fluid in at least one of the patient loop and the regenerationloop.

In an embodiment of any of the methods described herein, recirculatingdialysate fluid through the patient loop includes passing the fluidthrough a portion of a patient.

In an embodiment, the method is for continuous flow peritoneal dialysisand includes passing the dialysate fluid and the regeneration fluid pastopposite sides of a dialyzer membrane and regenerating the regenerationfluid after the regeneration fluid exits the dialyzer.

In an embodiment of the continuous flow peritoneal dialysis method,recirculating dialysate fluid through the closed patient loop includespassing the fluid through a sleeping patient.

In an embodiment of the continuous flow peritoneal dialysis method,recirculating dialysate fluid through the closed patient loop includespassing the fluid through a patient at nighttime.

In another embodiment, a method of moving fluid in a peritoneal dialysissystem is provided. The peritoneal dialysis method includes the stepsof: (i) continuously recirculating dialysate through a container in apatient loop; (ii) continuously recirculating dialysate through thecontainer in a regeneration loop; and (iii) continuously moving at leastone waste component from the patient loop to the regeneration loopthrough the container shared by both loops, the loops being closedexcept for said transfer through said container.

In an embodiment, the peritoneal dialysis method includes the step ofrecirculating dialysate through the regeneration loop at a differentrate than a rate at which dialysate is recirculated through the patientloop.

In a further method of the present invention, performing continuous flowdialysis includes multiple dialysis disciplines. The method includesperforming continuous flow peritoneal dialysis with a closed loopdialysis device at a first point in time and performing continuous flowhemodialysis via the same closed loop dialysis device at a second pointin time.

In an embodiment, the continuous flow peritoneal dialysis and thecontinuous flow hemodialysis are performed on the same patient.

In an embodiment, the method includes an intermediate step of removing adisposable cassette used with the device and coupling a new disposablecassette to the device.

In an embodiment, the method includes an intermediate step of removing adual lumen peritoneal dialysis catheter and replacing the catheter witha hemodialysis needle.

In an embodiment, the method includes an intermediate step of removing ahemodialysis needle and replacing the needle with a dual lumenperitoneal dialysis catheter.

One advantage of the present invention is to provide improved systemsand methods for performing dialysis.

Another advantage of the present invention is to provide improvedsystems and methods for performing automated continuous flow dialysissystems and methods.

A further advantage of the present invention is to provide regenerativedialysis systems and methods of operating same.

Still another advantage of the present invention is to provide aregenerative dialysis system that has clinical advantages.

Still a further advantage of the present invention is to provide aregenerative dialysis system that has economic advantages.

Yet another advantage of the present invention is to provide aregenerative dialysis system that has quality of life advantages.

Still further, an advantage of the present invention is to provide aregenerative dialysis system that reduces the amount of dialysis fluidneed to perform dialysis.

Another advantage of the present invention is to provide a closed loopdialysis system.

Other advantages of the present invention are to provide systems andmethods for performing both peritoneal dialysis and hemodialysis.

Additional features and advantages of the present invention aredescribed in, and will be apparent from, the following DetailedDescription of the Invention and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 schematically illustrates an embodiment of a dialysis systemaccording to the principles of the present invention.

FIG. 2 shows a multi-lumen patient fluid connector according to theprinciples of the present invention.

FIG. 3 schematically illustrates another embodiment of a dialysis systemaccording to the principles of the present invention.

FIG. 4 schematically illustrates a further embodiment of a dialysissystem according to the principles of the present invention.

FIG. 5 illustrates an embodiment of a disposable cassette according tothe present invention.

FIG. 6 illustrates another embodiment of a disposable cassette accordingto the present invention.

FIG. 7 illustrates a disposable cassette of the present inventionconnected to various fluid containers.

FIG. 8 schematically illustrates yet another embodiment of a dialysissystem according to the principles of the present invention.

FIG. 9 schematically illustrates an embodiment of a dialysis systemaccording to the principles of the present invention that provideshemodialysis.

FIG. 10 illustrates a combination container providing various componentsused in the dialysis systems of the present invention.

DETAILED DESCRIPTION

Generally, the present invention relates to dialysis systems and methodsof performing dialysis. In an embodiment, the present invention pertainsto continuous flow regeneration peritoneal dialysis systems and methods.In other embodiments the present invention pertains to non-continuousflow regeneration peritoneal dialysis, and regeneration hemodialysis,both continuous and non-continuous flow.

The dialysis system automatically performs dialysis therapy on apatient, for example during nighttime while the patient sleeps. Thepresent invention can provide true continuous flow dialysis therapy(fluid simultaneously flowing into and out of the patient), andautomatically regenerate spent dialysate into fresh dialysate that isagain used for the dialysis treatment. Continuous flow of dialysatetends to increase the efficacy of treatment by maximizing or maintaininga maximum osmotic gradient across the peritoneal membrane. Regenerationof dialysate by the present invention significantly reduces the amountof dialysate required for a treatment. For example, the amount ofdialysate fluid can be reduced from about fifty liters for CFPD therapyif performed by an existing cycler to about six to eight liters of samefor therapy with the present invention.

In a peritoneal dialysis embodiment of the present invention, the spentdialysate from the patient's peritoneal cavity passes through aregeneration unit and is regenerated into a useable dialysate. Theregenerated dialysate in a patient fluid loop is returned to thepatient's peritoneal cavity to further dialyze the patient. Theregeneration unit removes undesirable components in the dialysate thatwere removed from the patient, for example, excess water (ultrafiltrateor UF), toxins, and metabolic wastes, so that the dialysate can be usedfor further dialysis. Desirable components can be added to the dialysateby the system, such as glucose and electrolytes, for example. Theadditives assist in maintaining the proper osmotic gradients in thepatient to perform dialysis and provide the necessary compounds to thepatient.

Continuous flow peritoneal dialysis according to the present inventionmeans that when the patient is being dialyzed (e.g., dialysate is beingpumped to and removed from the peritoneal cavity), the dialysate isconstantly and simultaneously flowing into and out of the patient. Thedialysis system pumps fresh dialysate into the patient's peritonealcavity while simultaneously pumping spent dialysate out of theperitoneal cavity. Accordingly, the dialysis system can eliminate thedwell period inside the peritoneal cavity that is typical for existingdialysis systems. The flow rate of the continuous dialysate flow can beconstant or varied as desired, and is generally about 100-300 ml/min.

The dialysis system of the present invention can be controlled toprovide various dialysis therapies, as desired. Accordingly, even thoughthe dialysis system can provide continuous flow, the present inventionalso supports non-continuous flow or batch systems and methods. Also,the continuous flow into and out of the peritoneal cavity occurs duringthe main therapy treatment, so that a dwell during a last bag, forexample, does not detract from the continuous flow feature. Furthermore,the fluid pumping mechanisms of the present invention may provide forbrief intermittent fluid flow, such as the filling of a pump chamber,for example. The continuous fluid flow of the present invention isconsidered to include such brief intermittent fluid flow.

The dialysis systems and methods of the present invention provideadvantages compared to other dialysis systems and therapies, such asclinical advantages, economic advantages, and quality of lifeadvantages, for example. It is believed that the present invention hasclinical advantages, such as, improved blood pressure (“BP”) control,improved hematocrit (“HCT”) control, improved fluid volume control,improved preservation of residual renal function (“RRF”), improvedadequacy vs. the National Kidney Foundation's DOQI standard, higherefficiency (clearances/time), lower glucose absorption, glucoseprofiling and ultrafiltrate management, and reduced catheter channeling.

It is also believed that the present invention has economic advantages,such as, reduced therapy cost and reduced Epogen (“EPO”) usage. Further,it is believed that present invention has quality of life advantages,such as, increased awake time free from dialysis devices, improvedpatient access, reduced complexity, reduced self-administration ofdrugs, reduced therapy training, elimination of the need for having ahome water infrastructure, a reduced amount of fluid that the patientmust handle and manage, simpler prescriptions and elimination of patienttransportation to dialysis centers.

The dialysis systems and methods of the present invention more closelysimulate and replace continuous kidney functioning as compared tointermittent dialysis therapies. This, in turn, can contribute toimproved clinical outcomes (RRF, HCT, BP, for example) while minimallyimpacting the patient's lifestyle. The efficiency and convenience of thepresent invention provides patients with a renal replacement therapythat is relatively unrestrictive. This allows patients to have greaterfreedom from limitations experienced by dialysis devices and therapies.The present invention can provide easier entrance into early dialysistherapy because the system can enable the physician to retain apatient's RRF while minimally impacting the patient's lifestyle.

Dual Loop System

Referring now to the drawings and in particular to FIG. 1, a system 10for providing dialysis treatment to a patient needing same isillustrated. As illustrated in FIG. 1, two loops are provided: a patientloop (a recirculating patient fluid flow path) 12 and a regenerationloop 14 (a recirculating dialysate fluid flow path). However, it shouldbe noted that the present invention can be used in a system includingonly one loop or more than two loops. The patient loop 12 is used todialyze the patient 16 with dialysate in a peritoneal dialysisembodiment. The regeneration loop 14 also contains dialysate and is usedto regenerate the dialysate in the patient loop 12. In a hemodialysisembodiment, the patient loop 12 carries the patient's blood, and theregeneration loop 14 dialyzes the blood and regenerates the dialysate inthe loop 14.

As illustrated generally in FIG. 1, the patient loop 12 and theregeneration loop 14 are initially filled or primed with dialysate fluidfrom a bag 18 by pumping the dialysate through a pump, such as anultrafiltrate pump 19. FIG. 1 shows a single dialysate bag 18 for boththe patient and regeneration loops 12 and 14; however, separatedialysate bags and/or fluid pumps could be individually used for thepatient loop 12 and the regeneration loop 14. In a hemodialysisembodiment, the patient loop 12 can be primed with a suitable primingsolution, such as a saline solution, and then connected to the patient'sblood circulatory system.

The patient loop 12 is fluidly connected to the patient 16 by amulti-lumen patient fluid connector 20 and catheter. Referring to FIGS.1 and 2, the multi-lumen patient fluid connector 20 can have, forexample, a single housing 70 having more than one separate lumen 72 (topatient lumen) and 74 (from patient lumen), or separate housings eachhaving one of the lumens 72 and 74. In a peritoneal dialysis embodiment,the multi-lumen patient fluid connector 20 can be connected to a duallumen catheter 22 (illustrated in FIG. 1), such as a catheter disclosedin U.S. patent application Ser. No. 09/689,508, titled “PeritonealDialysis Catheters,” now U.S. Pat. No. 6,976,973, incorporated byreference, or other multi-fluid path patient access.

The dual lumen catheter 22 is implanted in the patient 16 and providesfluid flow access to the patient's peritoneal cavity. Two separatelumens 72 and 74 of the multi-lumen patient connector 20 are fluidlyconnected to separate lumens (not illustrated) of the dual lumencatheter 22. Fluid in the patient loop 12 can continuously flow throughthe patient fluid connector 20 simultaneously and continuously inmultiple directions, e.g. two different directions, into and out of thecatheter 22 and the patient 16. The multi-lumen patient fluid connector20 is described in further detail below in FIG. 2.

In a continuous flow embodiment, the patient loop 12 can be fluidlyconnected to the patient by any device or devices that provides forfluid to simultaneously flow into and out of the patient. For example,the patient loop 12 can be connected to the dual lumen catheter to twosingle lumen catheters.

In FIG. 1, the patient loop 12 has a patient fluid pump 24 that pumpsfluid through the patient loop 12. The fluid in the patient loop 12 ispumped from the patient 16 (the patient's peritoneal cavity in aperitoneal dialysis embodiment) through the patient fluid connector 20,through a dialyzer 26, back through the patient fluid connector 20, andis returned to the patient 16. In a peritoneal dialysis embodiment, thespent dialysate (laden with waste and excess water) in the patient loop12 exiting from the patient 16 is cleansed or regenerated by passingthrough the dialyzer 26. The waste, such as urea, creatinine and excesswater passes from the patient loop 12 across a dialyzer membrane 28 tothe regeneration loop 14 to produce fresh dialysate exiting the dialyzerin the patient loop 12. The fresh dialysate is returned to the patient16 for further dialysis treatment. In an embodiment, the fluid in thepatient loop 12 is continuously recirculated through the patient loop 12by the patient pump 24. Also, the dialyzer 26 provides a sterileindependent barrier between the patient loop 12 and the regenerationloop 14. Existing dialyzers used for dialysis is therapy are suitablefor use with the present invention, for example. Also, the membrane 28referred to in the dialyzer 26 includes any suitable filter material,such as hollow dialyzer fibers.

In a hemodialysis embodiment, the patient loop 12 is connected to thepatient's blood circuit rather than the peritoneal cavity. The patientpump 24 continuously recirculates the blood, as the dialyzer 26 removeswaste and excess from the blood.

The regeneration loop 14 removes the waste and excess water from thepatient loop 12. In the embodiment illustrated in FIG. 1, a fluid pump30, pumps dialysate fluid in the regeneration loop 14 continuously torecirculate the dialysate through the loop 14. The dialysate fluid pump30 pumps the dialysate from the dialyzer 26, through a sorbent cartridge32, and back to the dialyzer 26. The fluid in the regeneration loop 14flows past a side of the dialyzer membrane 28 opposite the side of themembrane 28 having the fluid in the patient loop 12. In an embodiment,the regeneration loop 14 provides for balanced fluid flow through thedialyzer 26, for example, by providing equal flow dialysate fluid pumps30, and/or balance chambers.

As mentioned above, waste and excess water passes from the fluid in thepatient loop 12, across the dialyzer membrane 28, to the fluid in theregeneration loop 14. The transfer across the dialyzer membrane 28occurs at least in part due to diffusion and concentration gradientsacross the membrane 28. Also, the system 10 in an embodiment maintains alower fluid pressure in the regeneration loop 14 relative to the patientloop 12. That is, there is a transmembrane pressure (“TMP”) across thedialyzer membrane 28. The fluid pressure differential draws fluid fromthe patient loop 12, across the dialyzer membrane 28, to theregeneration loop 14. This fluid pressure differential can be maintainedby removing fluid from the regeneration loop 14, for instance, by usingthe ultrafiltrate pump 19 to drain some of the fluid in the regenerationloop 14. The amount or rate of fluid removed from the regeneration loop14 by the ultrafiltrate pump 19 determines the amount or rate of fluidtransferring from the patient loop 12, across the dialyzer membrane 28,to the regeneration loop 14. This amount or rate equals the amount orrate of fluid removed from the patient 16 to the patient loop 12.

A sorbent cartridge or container 32 includes materials that absorbparticular compounds from the dialysate. For example, certain sorbentswithin the sorbent cartridge 32 may absorb uremic toxins, such as urea,creatinine, uric acid, and other metabolism by-products. By removingthese undesirable waste materials, the sorbent cartridge 32 at leastpartially regenerates the dialysate. The sorbent cartridge 32 includes abody having a fluid inlet 34 and a fluid outlet 36. One sorbentcartridge 32 according to the invention contains four layers ofmaterials, including a first layer of urease, a second layer ofzirconium phosphate, a third layer of zirconium oxide and a fourth layerof carbon. The interior of the cartridge 32 is constructed and arrangedso that the fluid entering the interior from the inlet 34 flows(preferably upward and uniformly) through the first layer, the secondlayer, the third layer, the fourth layer and finally through the outlet36.

The sorbent cartridge 32 can also use materials that selectively removecertain solutes from the dialysate. The selective materials can includea binder or reactive sorbent material capable of selectively removingurea, a binder or reactive sorbent material capable of selectivelyremoving phosphate and/or the like. The use of materials capable ofselective removal of solutes, particularly urea, enhances the cleaningefficiency of the system of the present invention such that the amountof dialysate necessary for effective treatment can be minimized.

The materials that can selectively remove solutes from solution, such asbinder materials, can include a variety of suitable and differentmaterials including, for example, polymeric materials that are capableof removing nitrogen-containing compounds, such as urea, creatinine,other like metabolic waste and/or the like in solution. In general,these types of materials contain a functional group(s) that chemicallybinds with urea or other like solutes.

For example, U.S. Pat. Nos. 3,933,753 and 4,012,317, each incorporatedherein by reference, disclose alkenylaromatic polymers containingphenylglyoxal that can function to chemically bind urea. In general, thephenylglyoxal polymeric material is made via acetylation performed in,for example, nitrobenzene followed by halogenation of the acetyl groupand treatment with dimethylsulfoxide as disclosed in U.S. Pat. Nos.3,933,753 and 4,012,317. Another example of a polymeric material that iscapable of selectively removing solutes, such as urea, from solutionincludes polymeric materials that contain a tricarbonyl functionalitycommonly known as ninhydrin as disclosed in U.S. Pat. No. 4,897,200,incorporated herein by reference. However, it should be appreciated thatthe present invention can include any suitable type of material orcombinations thereof to selectively remove solutes, such as urea, fromsolution as previously discussed.

In addition to absorbing certain materials from the dialysate, thesorbent cartridge 32 may also modify the dialysate in the regenerationloop 14 in other ways. For example, the materials in the sorbentcartridge 32 mentioned above or additional materials added to thecartridge 32 may modify the pH of the fluid passing through thecartridge 32. In an embodiment, the pH of the dialysate in theregeneration loop 14 is modified as needed to maintain a physiologiclevel. One sorbent cartridge 32 is described in further detail in a U.S.patent application titled “Method and Composition for Removing UremicToxins in Dialysis Processes,” Ser. No. 09/990,673, now U.S. Pat. No.7,241,272, incorporated herein by reference.

The sorbent cartridge 32 can also include a number of components inaddition to the sorbent materials capable of removing solutes from thedialysate. For example, the cleaning cartridge may have the capabilityto remove all or a portion of electrolytes, such as sodium, potassium,or the like, from the dialysate solution. In this case, an additionalsource of electrolytes in solution may be needed to replenish thedialysate after it has been cleaned. The cartridge may also beconfigured to release bicarbonate or the like into the system dependingon the type of sorbent material used. This can facilitate pH regulationof the dialysate. As necessary, the cartridge may be filtered to preventproteins, particulate matter or like constituents from leaching orexiting from the cartridge and into the dialysate.

Ultrafiltrate (excess water) removed from the patient 16 can be removedfrom the dialysis system 10 by draining the ultrafiltrate to a drain bag38 or other drain means. In one embodiment, the ultrafiltrate pump 19removes fluid from the regeneration loop 14 at the exit end of thedialyzer 26 through valves 40 and 42 to the drain bag 38, wherein thefluid contains the waste and excess water removed from the patient loop12 by the dialyzer 26. The drain pump 19 can remove fluid from theregeneration loop 14 continuously or intermittently (e.g., batchoperation), as desired.

The dialysis solution in the regeneration loop 14 is removed from thesystem along with the ultrafiltrate. Accordingly, a dialysateconcentrate is provided in a concentrate container 44 to supplynecessary compounds to the regeneration loop 14. The concentrate fromthe container 44 mixes with the dialysate in the regeneration loop 14and adds the compounds to the dialysate. The concentrate in anembodiment also includes other components that are provided to thepatient 16, for example, electrolytes. A concentrate pump 46 and a valve48 are provided to selectively pump the concentrate from the concentratecontainer 44 to the regeneration loop 14. The concentrate contributes tothe regeneration of the dialysis solution in the regeneration loop 14.

Although the fluids in both the patient loop 12 and the regenerationloop 14 are, in an embodiment, recirculated continuously through theirrespective loops, the various fluid pumps can be controlled by acomputer, processor, or microprocessor, collectively referred to hereinas a “controller” 200, to pump their respective fluids intermittently,if desired.

The dialysis system 10 in an embodiment is a closed, sterile system.Air, moisture and fluids from the environment around the dialysis system10 cannot enter into the patient loop 12 or the regeneration loop 14.The dialysis system 10 does permit fluids (such as ultrafiltrate) andair to exit the fluid loops 12, 14 and fluids (such as concentrate) tobe added to the fluid loops 12, 14 under controlled circumstances. Thedialysis system 10 is designed to prevent uncontrolled contact of thepatient and the regeneration loops 12 and 14 with the surroundingenvironment.

FIG. 1 schematically shows an example of a gas separator 50 in thedialysis system 10. The term “gas” is used herein to include gasses ingeneral, including air, carbon dioxide (“CO2”) and any other type of gasthat can become entrained in fluid loops 12 and 14. The regenerationfluid loops 12 and 14 can accumulate air for various reasons. Forexample, the fluid loops 12 and 14 may contain air prior to priming thesystem 10 with fluid or the storage containers may introduce air intothe fluid loops 12 and 14. The sorbent cartridge 32 may produce CO2 andintroduce the CO2 gas into the loops 12 and 14. The patient 16 can alsoproduce certain gasses, which become entrained in the dialysate andenter the loops 12 and 14.

It is desirable to remove gas from the fluid loops 12 and 14. The gasseparator 50 removes entrained gas from the fluid in the regenerationloop 14 and vents the gas to outside of the dialysis system 10. In thismanner, gas is purged from the regeneration loop 14. The gas separator50 includes a one-way vent, i.e., it permits gas to vent from the fluidloops 12 and 14 to the atmosphere but prevents gas outside of the fluidloops 12 and 14 from entering into the loops.

In one embodiment illustrated in FIG. 3, the gas separator 50 and thesorbent cartridge 32 of FIG. 1 are combined into a single device 102.One example of a gas separator 50/sorbent cartridge 32 combination isshown in the patent application titled “Method and Composition forRemoving Uremic Toxins in Dialysis Processes,” Ser. No. 09/990,673, nowU.S. Pat. No. 7,241,272, mentioned above. As illustrated in FIG. 1,however, the gas separator 50 can be a separate system component orincorporated into system components other than the sorbent cartridge 32.

It is also desirable to purge gas from the patient loop 12. In anembodiment, an additional gas separator (not illustrated) can beprovided in the patient loop 12, which vents to the atmosphere. Inanother embodiment, the gas can be removed from the patient loop 12, fedto the gas separator 50 in the regeneration loop 14, e.g., via line 51,and vented to the atmosphere.

In an embodiment, one or more gas sensor(s) 52 are provided at desiredlocations along the patient loop and/or the regeneration loop 14 todetect gas in the system 10. In an embodiment, gas sensors 52electrically connect or are otherwise in communication with the systemcontroller, which monitors gas content in the loops 12 and 14. Thecontroller can control the system to perform any desired function inresponse to the gas, such as, stopping fluid flow, changing thedirection of fluid flow, or removing the gas. The gas separator 50 canbe any suitable device, which separates gas from fluid known to those ofskill in the art. Gas separators, such as the separator 50, can be usedwhich separate and vent the gas without being controlled by the systemcontroller. In an embodiment, the gas separator 50 absorbs the gasrather than venting it to the atmosphere as illustrated.

In an embodiment, the dialysis system 10 contains a fluid heater 54,shown schematically in FIG. 1. The fluid heater 54 heats the fluid inthe patient loop 12 to a desired temperature for supplying the fluid tothe patient 16. The fluid heater 54 is an in-line heater (continuousflow heater) that heats the fluid to the desired temperature as thefluid flows continuously past the heater 54. In other embodiments,heaters other than in-line heaters can be used, for example, bulkheaters. The fluid heater 54 is shown in FIG. 1 in the patient loop 12at the fluid supply to the patient 16. However, the fluid heater 54 canbe positioned at other locations in the patient loop 12 and theregeneration loop 14, if desired. In another embodiment, one or both ofthe loops 12 and 14 include one or multiple heaters 54.

In an embodiment, the fluid heater 54 is a dual heater, including aninfrared heater 56 and a plate heater 58. An example of such a dualheater 54 is disclosed in a patent application entitled, “Medical FluidHeater Using Radiant Energy,” Ser. No. 10/051,609, now U.S. Pat. No.7,153,285, incorporated herein by reference. Both the infrared heater 56and the plate heater 58 are in-line heaters that heat the medical fluidthat flows continuously past the heaters 56, 58. The radiant energy orinfrared heater 56 emits infrared energy that is directed to andabsorbed by the fluid in the patient loop 12, thereby heating the fluid.The radiant energy or infrared heater 56 is a primary or high capacityheater which can heat a relatively large volume of cold fluid to adesired temperature in a short period of time.

The plate heater 58 is a secondary or maintenance heater which has arelatively lower heating capacity relative to the infrared heater 56.The plate heater 58 uses electrical resistance to increase thetemperature of a plate that in turn heats the fluid flowing near theplate.

The heater 54, which includes both high and low capacity heaters,provides an efficient heater design that accommodates various fluidheating requirements. For example, the radiant or infrared heater 56 isparticularly useful for quickly heating cool dialysate (high heat energydemand) that is supplied to the dialysis system 10, such as at theinitial system fill or if there is severe heat loss during dialysistreatment. The temperature of the dialysate at initial system fill canbe quite low, such as 5° C. to 10° C. if the fluid is stored in coldambient temperature.

The plate heater 58 is particularly useful to maintain a desiredtemperature (lower heat energy demand) of the fluid being supplied tothe patient, e.g., due to a normal amount of heat loss during dialysistreatment. The infrared heater 56 provides for the high heat demand in asmall amount of fluid exposure space, while the plate heater 58 providesfor maintenance heat demand and requires a lesser amount of input energycompared to the infrared or radiant heater 56. Furthermore, the heatingcapacity of the heater 54 is increased if both the infrared and plateheaters 56 and 58 are used together to heat the fluid.

The infrared heater 56 and the plate heater 58 can be arranged invarious configurations relative to each other. The heaters 56 and 58 inan embodiment are arranged so that the fluid passes by the heaterssequentially (e.g., first the radiant or infrared heater and then theplate heater). In another embodiment, the fluid passes by the heaterssimultaneously (both heaters at the same time) or in the reverse order.The fluid flow path past the heaters 56 and 58 can be a common flow pathfor both heaters 56 and 58 or include independent flow paths for eachheater 56 and 58. Besides radiant or infrared electrical resistanceheating, other types of heating such as convective, inductive, microwaveand radio frequency (“RF”) heating may be used.

In an embodiment, temperature sensors are provided at desired locationsalong one or both of the patient loop 12 and the regeneration loop 14.The temperature sensors monitor various fluid temperatures and areconnected to the system controller to control the fluid temperatureswith the heater 54. When two or more heaters, such as the infraredheater 56 and the plate heater 58, are provided in the dialysis system10, the system 10, in an embodiment, can include separate temperaturesensors for each heater so that each heater can be controlledindividually.

The dialysis system 10 in an embodiment also includes various othersensors to monitor various parameters. For example, fluid pressuresensors 60 and 62 are provided in the patient loop 12 of FIG. 1. Thefluid pressure sensors 60 and 62 electrically couple to or otherwisecommunicate with the controller to provide a signal that indicates therespective fluid pressure at that location. Based on the signals fromthe pressure sensors 60 and 62, the controller operates the fluid pumpsand valves to obtain and maintain desired fluid pressures in the loop 12running to and from the patient 16.

In an embodiment, the pressure sensors 60 and 62 are non-invasivepressure sensors. That is, the pressure sensors 60 and 62 do notphysically contact (and possibly contaminate) the medical fluid ordialysate. The pressure sensors 60 and 62 measure the medical fluidpressure and help to maintain a steady flow within the closed fluidsystem. Of course, other fluid devices, such as flow rate sensors,pressure gauges, flowmeters, or pressure regulators, which are notillustrated FIG. 1, may be provided in any suitable quantity and at anydesired location within either or both of the patient loop 12 and theregeneration loop 14.

In the illustrated embodiment, the system 10 includes an ammonia sensor64. The ammonia sensor 64 measures the concentration of ammonia (NH3)and/or ammonium (NH4) in the fluid. Ammonia and ammonium are produced bythe regeneration sorbent cartridge 32 as a by-product of the ureacatalysis urease. The ammonia and ammonium are normally removed by acation exchanger in the sorbent cartridge 32. However, the dialysissystem 10 monitors the fluid for ammonia/ammonium concentrations withthe sensor 64 to confirm that the ammonia and ammonium are being removedand remain below safe threshold levels for the patient 16. The totalammonia and ammonium in solution is primarily determined by threeparameters: ammonia or ammonium, pH, and solution temperature. Bymeasuring these parameters (or adjusting a parameter, such as adjustingthe pH to a desired level), the total amount of ammonia and/or ammoniumin the dialysate can be determined.

One sensor 64 according to the present invention is described in apatent application entitled, “Ammonia and Ammonium Sensors,” Ser. No.10/024,170, published as U.S. Pub. No. 2003/0113931, now abandoned,incorporated herein by reference. The sensor 64 determines the totalammonia and ammonium content of an aqueous solution. The sensor 64includes a hydrophobic ammonia sensing membrane, a pH indicator orconditioner, a temperature sensor and an optical sensor. An algorithmstored in the controller calculates the combined ammonia and ammoniumcontent from the three parameters (e.g., NH3, pH and temperature). Theammonia gas, which is highly soluble in water, is quantified by thehydrophobic sensing membrane that changes color based on the quantity ofammonia gas diffused into it. A multi-wavelength optical sensorcontinuously measures the membrane color through a transparent window.The sensor 64 achieves a non-intrusive measurement by the using theoptical sensor to monitor color changes in the disposable membraneplaced inside the fluid path.

In the illustrated embodiment of FIG. 1, the dialysis system 10 alsoincludes one or more fluid flow measurement devices or volume sensors 66that measure the volume of the medical fluid pumped eitherintermittently or cumulatively through one or both of the loops 12 and14. In an embodiment, the fluid flow measurement device 66 measures theamount of fluid supplied to the patient 16 by the patient loop 12.Additionally or alternatively, the regeneration loop 14 and/or theultrafiltrate drain line employ one or more fluid flow measurementdevices 66 to measure the amount of ultrafiltrate removed from thepatient 16. Various types of fluid volume measurement or flowratedevices can be used with the dialysis system 10, such as orifice plates,mass flow meters or other flow measuring devices known to those of skillin the art.

FIG. 1 schematically illustrates one embodiment of a flow measurementdevice or volume sensing device 66, which includes a capacitance sensorthat measures the volume of fluid pumped through a chamber, such as apump chamber (dotted lines designating the device 66 shown encirclingthe pumps 19, 24 and 30). The capacitive fluid sensor 66 is disclosed ingreater detail in the patent application entitled, “Capacitance FluidVolume Measurement,” Ser. No. 10/054,487, now U.S. Pat. No. 7,107,837,incorporated herein by reference.

The capacitance C between two capacitor plates changes according to thefunction C=k×(S/d), wherein k is the dielectric constant, S is thesurface area of the individual plates and d is the distance between theplates. The capacitance between the plates changes proportionallyaccording to the function 1/(R×V), wherein R is a known resistance and Vis the voltage measured across the capacitor plates.

In one embodiment of the capacitance sensor 66, the sensor cooperateswith the pump chamber. The pump chamber in an embodiment includes shellsor walls defining a fixed and known volume and a pair of flexiblemembranes operating between the shells, which expand to fill with fluidand contract to discharge fluid. The capacitance sensor 66 includescapacitor plates disposed on opposite sides of the pump chamber. As thevolume of fluid in the chamber or fluid pump changes (i.e., the pumpchamber fills or empties), the dielectric property of the varying fluidsbetween the capacitance plates changes. For example, the combineddielectric constant of dialysate and air changes as dialysate replacesair (or air replaces dialysate) within shells of the constant volumechamber. This change in the overall dielectric constant affects a changein the capacitance between the two plates, which causes a change involtage across the capacitance plates, wherein the change in voltage canbe sensed by a voltage sensing device. The controller monitors thechange in voltage by the voltage sensing device and correlates (after acalibration of the sensor) the capacitance change to an amount of fluidpumped through the chamber.

In another embodiment, the volume of the chamber or the pump chamber canvary, e.g., by movement of one or both the shells of the chamber. Inthis embodiment, the capacitance between the capacitor plates changesdue to a changing distance d between the plates and/or a changingsurface area S of one or more of the plates, wherein the dielectricconstant k is static because only one fluid resides at all times betweenthe capacitor plates. In a further alternative embodiment of themeasurement device 66, the capacitance C between the capacitor plateschanges based on any combination or all three of a change in dielectricconstant k, distance d and surface area S.

The controller collects a multitude of voltage signals from capacitancechanges from sensor 66 due to a plurality of chamber fill and draincycles, wherein the controller calculates a total volume of medicalfluid pumped over a length of time or number of pump cycles. Thecapacitance sensor 66 monitors the medical fluid, e.g., dialysate, flowinto or from the pump chamber on a real time basis, and in anon-invasive manner.

The capacitance sensor 66 enables the dialysis system 10 to maintain thevolume of fluid that is provided to the patient 16 at desirable amountsand flow rates. Maintaining the fluid flow to the patient 16 withindesired levels is particularly advantageous for peritoneal dialysistherapies.

Also, it is desirable to maintain the fluid provided to the patient atphysiologic levels. Physiologic control, such as sensing and/oradjusting parameters of the fluids, can take place at various locationsin the dialysis system 10, including the patient loop 12 and theregeneration loop 14. For example, as mentioned above, the sorbentcartridge 32 may include a pH sensor that adjusts the fluid in theregeneration loop 14, which then adjusts the fluid in the patient loop12 via the dialyzer to be at a desired physiologic level.

Dual Lumen Connector

Referring now to FIG. 2, one embodiment of a dual lumen patient fluidconnector 20 of the present invention is described in further detail. Asdescribed above, the dual lumen connector 20 includes a housing 70having a lumen 72 for providing fluid to the patient lumen and aseparate lumen 74 to remove fluid from the patient. Separate housingseach having one of the lumens 72 and 74 may be provided. The patientinflow lumen 72 connects to a patient inflow tube 76 of the patient loop12. Similarly, the patient outflow lumen 74 connects to a patientoutflow tube 78 of the patient loop 12. A removable end cap 80 isprovided to seal a cavity 82 defined by the housing 70. The cavity 82surrounds or abuts the lumens 72 and 74 and provides a connection areafor the dual lumen catheter 22 (FIG. 1) to insert into the cavity 82 andmate with the lumens 72 and 74.

The housing 70, lumens 72 and 74 and the end cap 80, in an embodiment,are made of any material suitable for medical applications, such asplastic for example. In an embodiment, one of the lumens, e.g., thepatient inflow lumen 72 extends further into the cavity 82 than theother lumen, which helps facilitate mating of the connector 20 to thecatheter 22. In another embodiment both lumens 72 and 74 extend into thecavity 82 the same or different distance.

The dialysis system 10, particularly the patient loop 12, can be primed,e.g., filled, with the end cap 80 in sealing engagement with the housing70. The arrows 84 and 86 figuratively illustrate the recirculating fluidflow through the dual lumen connector 20. The system 10 can thereforerun without a fluid connection to the patient. Also, the system 10 mayinclude a patient by-pass line between the patient inflow and outflowtubes 76, 78 to allow fluid flow through the patient loop 12 whileby-passing the patient 16. The end cap 80 is removed, e.g., pulled offor unscrewed, to expose the cavity 82 and the patient inflow and outflowlumens 72 and 74, respectively, for connection to the dual lumencatheter 22.

In an alternative embodiment, the patient fluid loop 12 directlyconnects to the dual lumen catheter 22 or to two separate single lumencatheters. In a further alternative embodiment, the connector 20 isadapted to connect to two separate single lumen catheters. In yetanother alternative embodiment, two separate connectors link singlelumen catheters to incoming and outgoing lines of the patient fluid loop12. Other configurations are also contemplated by the present invention.

Alternative Dual Loop System with Balanced Flow

Referring now to FIG. 3, a system 100 for providing dialysis treatmentto a patient is illustrated. The system 100 of FIG. 3 includes many ofthe same components as the system 10 of FIG. 1. For example, the system100 includes two loops, a patient loop 12 and a regeneration loop 14.The patient loop 12 passes a medical fluid, dialysate or blood, to andfrom a patient 16. In a peritoneal dialysis embodiment, the patient loop12 and regeneration loop 14 are initially filled and primed withdialysate from a dialysate bag 18. The patient loop 12 fluidly connectsto the patient 16 by the multi-lumen patient fluid connector 20described above in connection with FIG. 2. In a peritoneal dialysisembodiment, the multi-lumen connector 20 connects to a dual lumencatheter 22. In a hemodialysis embodiment, the patient loop 12 fluidlyconnects to a multi-lumen hemodialysis needle or other patient bloodaccess device.

The system 100 includes multiple patient fluid pumps 24 a and 24 b. Ithas been found that using multiple pumps, such as the patient fluidpumps 24 a and 24 b, creates a steadier flow of fluid to and from thepatient 16 within the patient loop 12. For example, fluid may be exitingthe fluid pump 24 a while the fluid pump 24 b is filling with fluid.Balance chambers can be provided, in an embodiment, to balance fluidflow.

The system 100 includes the dialyzer 26 having the dialyzer membrane 28.The spent dialysate (or blood in a hemodialysis embodiment) laden withwaste and excess water in the patient fluid loop 12 is cleaned orregenerated when recirculated through the dialyzer 26. The waste passesfrom the patient loop 12 across the dialyzer membrane 28 to theregeneration loop 14. In the regeneration loop 14, the fluid pumps 30,30 continuously pump the regenerating dialysate through the combinationdevice 102, which includes the absorbent cartridge 32 and the gasseparator 50. The system 100 includes dual dialysate fluid pumps 30 toprovide balanced flow within the regeneration loop 14. That is, one ofthe fluid pumps 30 is being emptied of fluid while the other pump 30 isbeing filled with fluid. In an embodiment, balance chambers can beprovided for balancing fluid flow.

The system 100 can drain ultrafiltrate and other fluids into the drainbag 38. An ultrafiltrate pump 19 pumps the ultrafiltrate and fluids fromthe patient loop 12 or the regeneration loop 14, for example throughvalves 40 and 42, into the drain 38. The system 100 also provides theability to collect fluid in a twenty-four hour collection bag 39 forevaluation of the dialysis therapy.

In an embodiment, one of the patient fluid pumps 24 a or 24 b pullsdialysate fluid from either the dialysate bag or container 18 or thelast bag 21. The last bag 21 includes a volume of fluid that is placedin the patient's peritoneal cavity just prior to the end of the dialysistreatment. The patient with the dialysate from the last bag 21 in theperitoneal cavity disconnects from the system 100 and is able to performdaily activities. The next dialysis therapy begins with draining thelast bag from the patient.

The system 100 includes a concentrate container 44, a concentrate pump46 and valves 48. The concentrate pump 46 provides concentrate from theconcentrate container 44 to the regeneration loop 14, for example intothe fluid line exiting from the outlet 36 of the combination absorbentcartridge and vent 102. The concentrate container 44 supplies necessarycompounds, such as electrolytes and osmotic agents, to the regenerationloop 14 of the system 100 to maintain the desired concentrations ofthose components.

Besides the concentrate that is contained in the concentrate container44, the system 100 regenerates dialysate through the regeneration loop14 and does not require fluids from an outside source. Hence the system100, as are each of the systems described herein, is completely closedto the outside. The systems of the present invention are thus “closedloop systems”. The closed loop nature of the patient loop 12 and theregeneration loop 14 enables the loops to run continuously withoutabsorbing or gathering outside contaminants. The closed loop systems ofthe present invention also maintain sterility by preventingcontamination from the environment.

The system 100, like the system 10, may generate gases over time, suchas air and CO2. The system 100 provides a plurality of gas sensors 52that detect the various gases that may be in the system 100. In thesystem 100, the gas sensors 52 are provided at an air separator whichseparates gas from the fluid in the patient loop 12. A gas separationline 51 feeds the separated gas from the patient loop 12 to the inletside 34 of the combination absorbent cartridge and gas separator device102. The gas is then purged out of the system 100 by the gas separator50. The gas separator 50 maintains the closed loop structure of thesystem 100 by preventing contaminants from entering the system 100. Forexample, the gas separator 50 can include a microbial filter whichallows gas to exit the system 100, but prevents contaminants fromentering the system 100. In another embodiment, the gas from the patientloop 12 may be purged from the system 100 by a separate gas purge deviceat the patient loop 12. The gas sensors 52, in an embodiment, can sendan electronic signal to the controller (not illustrated). When thecontroller detects gas, the controller causes one or more valves toopen, wherein the gas from the loop 12 is fed to a one-way vent andpurged from the system 100.

The system 100 further includes the inline heater 54, which, in anembodiment, includes an infrared or radiant heater 56 and a plate heater58 as described above. In an embodiment, the heater 54 has an airseparator which allows air to exit port 59 on be purged from the system.

The system 100 further includes an orifice device 61 that stabilizes thedifferential pressure in the dialyzer 26 across the membrane 28. Thatis, the orifice device 61 can restrict the flow in the patient loop 12to create a pressure differential between the patient side andregeneration side of the dialyzer 26. The pressure gradient ordifferential occurs across the membrane 28 in which the patient loop 12having a higher fluid pressure than the regeneration loop 14. Theorifice device can be a fixed or variable flow restriction and canprovide a fixed or variable pressure differential. Also, the orificedevice 61 can be electrically coupled to and operated by the controller,which can activate, e.g., open or close the orifice device as necessary.

The pressure differential across the membrane 28 (higher pressure in thepatient loop 12 and lower pressure in the regeneration loop 14) createdby the orifice 61 assists in maintaining a greater pressure in theregeneration loop 14 relative to atmosphere pressure external to thesystem 100. The positive pressure in the regeneration loop 14 relativeto the external atmosphere pressure aids in ensuring that external airis not pulled from the surrounding environment through the air vent 50into the regeneration loop 14, i.e., air can only exit the system 100and not enter into the system 100. Accordingly, the orifice 61contributes to the closed loop nature of the system 100.

The system 100 provides a number of temperature sensors, such as sensors63, 65 and 67, which monitor temperatures at various points within thepatient loop 12. The controller uses the sensed temperatures to maintaina desired temperature within the patient loop 12. As illustrated, thetemperature sensor 63 is located at or on the heater 54, which enablesthe system 100 to sense a temperature at a point very close to theconstituent heaters 56 and 58, and to control the heaters 56, 58.

The system 100 further includes one or more pressure sensors 60 and 62,which reside at various points along the patient fluid loop 12. Thepressure sensors 60 and 62 can be used to prevent excessive positive ornegative pressures from being applied to the patient. The pressurewithin the system can be controlled by, e.g., activation of the patientfluid pumps 24 a, 24 b.

The system 100 also monitors the absorbent cartridge 32 with anammonia/ammonium sensor. Sample fluid exiting the absorbent cartridge 32can be directed through a pH adjuster 71 to force the ammonia/ammoniumequilibrium balance to a particular level. The amount of ammonia and/orammonium in the sample fluid is measured by a sensor 73. Accordingly,the effectiveness of the cartridge 32 to remove ammonia/ammonium afterconversion from urea can be monitored. When the concentration of ammoniaand/or ammonium reaches a threshold level, the system can produce asignal, or take other action such as shutting down, that indicates thecartridge 32 needs to be replaced.

Of course, the system 100 can monitor other fluid parameters and takeappropriate action, as desired. Also, sample fluid can be taken at anydesired location in the system 100. Further, fluids in the patient andregeneration loops 12, 14 can be tested or monitored directly ratherthan taking samples.

The system 100 also includes fluid volume sensors 66 which in anembodiment are capacitance sensors that sense a change in capacitanceoccurring between two capacitor plates. The capacitor plates surroundthe pumps 24 of the patient loop 12, the pumps 30 of the regenerationloop 14 and the pumps leading to the fluid containers. Each of the pumps24 a, 24 b, pump 30, pump 19 and pump 46 can be provided with thecapacitance volume sensor 66 of the present invention. Each of thesensors 66 sends a discrete signal to the controller (not illustrated),which measures and monitors the volume of fluid flowing through the pumpchambers of the respective pumps. In other embodiments, any suitablefluid volume measurement device can be used.

Alternative Dual Loop System with Gas Separation

Referring now to FIG. 4, a system 110 of the present invention isillustrated. The system 110 of FIG. 4 is similar to the system 100 ofthe FIG. 3 and is a closed loop system. The system 110 includes variouscomponents of the system 100 described previously. The system 110 has aregeneration loop 14 which has a pair of balanced dialysate fluid pumpscreated by a pair of chambers 75 that operate with the pumps 30. Eachbalance chamber 75 includes a pair of chambers separated by a membrane.When one of the pumps 30 fills one side of the chambers of the balancechambers 75 fills with medical fluid, the membrane is forced toward theother chamber, which forces fluid out of that chamber. In this way, themembrane acts to balance the flow of the dialysate fluid within theregeneration loop 14, so that there is no net flow of fluid across thedialyzer membrane except for the flow needed to replace the fluidremoved by the ultrafiltrate pump 19.

Another difference of the system 110 of FIG. 4 compared to the system100 of FIG. 3 is the gas separator 50. The gas separator 50 in theillustrated embodiment of the system 110 is independent of the sorbentcartridge 32. The gas separator 50 accepts gas through a vent line 51that runs from the exit port 59 of the heater 54 in the patient fluidloop 12. One or more gas sensors 52 monitor gas in the vent line 51 asillustrated.

Disposable Cassettes

Referring now to FIG. 5, a dialysis system having a disposable cassette120 according to the present invention is illustrated. In this variationof the system 100 of FIG. 3, the pumps 30 of system 120 draw fluid fromaccumulators A4 and A6 and discharge into accumulators A3 and A5.Accumulators A3 to A6 smoothen the dialysate flow by dampening pressurefluctuations during pumping. In an embodiment, much of the flow logicand at least parts of the flow devices described above are provided inthe disposable cassette 120. The cassette 120, in an embodiment, has arigid plastic body 122 with various fluid flow channels and fluidchambers defined in the body 122. A flexible membrane is bonded to thefront side of the cassette body 122 shown in FIG. 5. The membrane coversthe fluid channels and chambers and is sealed to the body 122 around thechannels and chambers. Accordingly, the membrane forms a wall of thefluid flow paths and fluid chambers. Similarly, the back side of thecassette body 122 may also be covered with a membrane.

The body 122, in an embodiment, is approximately 12 inches high, eightinches wide, and one inch deep. The flow components and flow linesdefined by the body 122 fluidly connect to other system components.Also, pump actuators, valve actuators, sensors and other systemcomponents may interface with the cassette 120.

Specifically, the body 122 provides a portion of the closed patient theregeneration loops 12 and 14. The dual lumen catheter 22 that insertsinto the peritoneal cavity of the patient 16 connects to the dual lumenconnector 20 outside of the body 122 of the disposable cassette 120. Thepatient loop 12 extends from an exit port 124 of the dialyzer 26 to avalve chamber 126 defined by the body 122. The patient fluid loop 12includes a series of manifolds and fluid flow paths that fluidly connectto the patient fluid pump(s) 24. The patient fluid pump 24 pumps thedialysate through the patient 16 and into an inlet 128 of the dialyzer26.

The patient fluid loop 12 also connects via pathways defined by the body122 of the disposable cassette 120 to various medical fluid bags. Forinstance, the dialysate fluid bag 18, which is maintained outside of thedisposable cassette 120, fluidly connects to a line 130 leading to thepatient fluid loop 12. Similarly, the last bag 21 also connects via aline defined by the body 122 to the line 130 that fluidly communicateswith the patient fluid loop 12. The line 130 defined by the body 122also fluidly communicates with the ultrafiltrate drain 38.

The body 122 of the disposable cassette 120 also defines chambers forthe concentrate pump 46 and the ultrafiltrate pump 19. The concentratepump 46 fluidly connects to an external concentrate bag 44. Thetwenty-four hour collection bag 39 described above fluidly connectsalong with the drain 38 to a fluid line defined by the body 122 thatruns to the ultrafiltrate pump 19.

The disposable cassette 120 provides fluid flow paths and defineschambers and other types of fluid orifices for the fluid flow componentsdescribed above. Specifically, the body 122 of the disposable cassette120 defines a patient fluid pump chamber 24 and dialysate fluid pumpchambers 30. The disposable cassette 120 mounts to a separatenon-disposable housing that includes the mechanical workings of the flowcomponents, such as the pumps. The pump chambers are bounded on one sideby a flexible membrane (not illustrated) that is positioned adjacent toand driven by the pump plungers of the non-disposable housing.

At least one side of the cassette 120 is covered with the flexible,e.g., plastic membrane (not illustrated). The disposable cassette 120plugs into a cavity or portion of the non-disposable housing (notillustrated). The housing provides the actuators for each of the pumpsherein described, e.g., the patient pumps 24, the dialysate pumps 30,the ultrafiltrate pump 19 and the concentrate pump 46. The housing alsoprovides the actuators for the various valve chambers defined by thebody 122 of the cassette 120, e.g., valve chamber 126. The moreexpensive mechanical and electromechanical pieces of the flowcomponents, e.g., the pump actuators and valve actuators, are kept andreused in the housing.

The disposable cassette 120 provides sterile, disposable fluid pathways,such as the pump chambers and the valve chambers. The actuators of thenon-disposable housing press against the flexible plastic membrane atthe pump chambers and valve chambers to force or allow fluid through thesystem. When the pump actuator pulls back from pressing against themembrane, the membrane returns to its normal shape and no longer exertsa force on the fluid within the pump chamber. The pump chamber fillswith fluid as the membrane is drawn back. Also, the membrane can bepositively drawn back by, for example, the pump actuator or vacuumpressure. The pump has thus made a cycle.

The body 122 of the disposable cassette 120 also defines at least aportion of a mounting area for housing the ammonia, ammonium or pHsensors or adjustors. In the illustrated embodiment, the disposablecassette 120 defines an area for housing the pH adjustor and adisposable colormetric membrane (which changes color based on theammonia/ammonium concentration) of the ammonia/ammonium sensor 73,wherein the fluid within the body 122 of the cassette 120 can fluidlycommunicate with the sensor. The optical color reader of theammonia/ammonium sensor 64 is disposed in the non-disposable housing(not illustrated), wherein the sensor can receive electrical power asneeded. If a pH sensor is used instead of the pH adjustor 71, a reusableportion of the pH sensor can also be located in the housing.

The housing also provides the in-line heater 54 and in an embodimentprovides one of either the radiant heater 56 and the plate heater 58,which is described in detail in the patent application entitled,“Medical Fluid Heater Using Radiant Energy,” Ser. No. 10/051,609, nowU.S. Pat. No. 7,153,285, mentioned above. Further, the housing providesone of the capacitor plates of the fluid volume sensor 66 beneath one ormore of the pump actuators, as described in detail in the patentapplication entitled, “Capacitance Fluid Volume Measurement,” Ser. No.10/054,487, now U.S. Pat. No. 7,107,837, mentioned above.

Referring back to the cassette 120 of FIG. 5, the cassette 120 has anin-line heating fluid heating path 123 for heating the fluid. The fluidin the heating path 123 is heated by a heater external to the cassette.

The cassette 120 also has one or more gas separators 125 which separategas from fluid in the cassette 120. The gas separators 125 feed theseparated gas through a line 127 to a vent 129.

The closed loop system of the present invention enables at least onewaste component to pass through the membrane 28 of the dialyzer 26 fromthe patient fluid loop 12 to the regeneration loop 14. The patient loop12 extending outside of the body 122 fluidly connects to a valve chamber132 defined by the body 122. The regeneration loop 14 includes manifoldsections defined by the body 122 and leads to pump chambers 30. Theclosed loop system prevents air or other fluids from entering thesystem.

The pump chambers 30 fluidly communicate with the sorbent chemicalcartridge 32 and the gas separator 50 of the combined device 102. Theregeneration loop 14 extends from the outlet 36 of the combined device102 and returns to the body 122 of the disposable cassette 120 throughthe valve chamber 134. From the valve chamber 134, the regenerateddialysate is pumped through the pump chambers 30 and into the manifoldsystem defined by the body 122.

Referring now to FIG. 6, another closed loop system having anotherdisposable cassette 140 is illustrated. This embodiment of thedisposable cassette 140 of the present invention includes many of thesame flow components and flow chambers as the cassette 120 of FIG. 5.The cassette 140, however, only includes a single regeneration pump body30. The cassette 140 in general, is less complicated than the cassette120 and illustrates that the disposable cassettes of the presentinvention may be adapted for different embodiments of the closed loopdialysate regeneration systems described herein.

Like the cassette 120 of FIG. 5, at least one side of the cassette 140is covered with a flexible, e.g., plastic membrane (not illustrated).The disposable cassette 140 plugs into a non-disposable housing (notillustrated) that provides the actuators for the various pumps, e.g.,the patient pump 24, the dialysate pump 30, the ultrafiltrate pump 19and the concentrate pump 46. The housing also provides the actuators forthe various valve chambers defined by the body 122 of the cassette 140.The more expensive mechanical and electromechanical pieces of the flowcomponents, e.g., the pump actuators, are again kept and reused in thehousing. As described above, the actuators press against the flexibleplastic membrane at the pump chambers to force fluid through the system.

As illustrated in both FIGS. 5 and 6, the disposable cassette 120 or140, in combination with certain external devices such as the dialyzer26, sorbent cartridge and gas separator device 102 and the fill anddrain bags, provides completely closed loop systems. The only make-up oradditional fluid that the regeneration system uses is that of theconcentrate from the concentrate bag 44, which seals to a device withinthe body 122 of the cassettes 120 and 140. Also, other than the systemsbeing connected to a patient, fluids and air cannot enter the closedloop system.

Referring now to FIG. 7, a schematic diagram illustrates the differentphysical components of a disposable set of the regeneration systems ofthe present invention. The disposable set is intended to be used for asingle dialysis therapy and then discarded. Another disposable set isused for the next dialysis therapy. Each of the above-described systems10, 100 and 110 in an embodiment includes a disposable cassette, such asthe cassette 120 or 140. The disposable cassette 120 or 140 provides aport 141 that connects to the concentrate bag 44 via a line 147. Thecassette provides a port 142 that fluidly connects to the drain bag 38via a line 148. The cassette provides a port 143 that fluidly connectsto the last bag 21 via a line 149. The cassette defines a port 144 thatfluidly connects to the dialysate bag 18 via a line 150. The cassetteprovides ports 145 and 146 that run to and from the dual lumen connector20 via patient lines 151 and 152, respectively.

In an embodiment, each of the lines 147 to 152 are made of medical gradetubing, such as a flexible, sterile and inert plastic such aspolyethylene, polystyrene, polypropylene or polyvinylchloride (“PVC”).In an embodiment, the bags and the lines are clear so that the patientor operator can see fluids traveling from the bags and through the linesto a cassette 120 or 140. The lines 147 to 152 connect to the ports 141to 146 via any type of medical fluid connection known to those of skillin the art. In an embodiment, the connections are quick-type connectionsthat enable the patient or operator to easily remove the line from itsmating port.

The disposable cassette 120 or 140 includes at least one port 153 thatfluidly connects to at least one outlet port 154 of the gas separator 50or combination device 102. The disposable cassette 120 or 140 includesat least one port 155 that fluidly connects to at least one inlet port156 of the sorbent cartridge 32 or combination device 102. The linesconnecting the disposable cassette 120 or 140 to the sorbent cartridge32, gas separator 50 or combination device 102 including same are madeof medical grade tubing, such as a flexible, sterile and inert plasticsuch as polyethylene, polystyrene, polypropylene or polyvinyl chloride.

Alternative Dual Loop System

Referring now to FIG. 8, an alternative closed loop regenerative system160 is illustrated. The system 160 is shown schematically, however, thesystem 160 may employ the disposable set described above such as thedisposable cassette, the fluid pumps, the various sensors, valves andcontroller. The system 160 includes a patient fluid loop 12 and aregeneration loop 14.

When dialysate is removed from the peritoneal cavity of the patient 16,the solution passes through an activated charcoal and anion exchanger162. The activated charcoal of the filter or exchanger 162 removes uricacid, creatinine, small molecular weight organics and middle molecules.The anion exchange column of the exchanger 162 removes phosphate. Thesolution exiting the filter or exchanger 162 enters a solution ordialysate bag 18. The dialysate entering the solution bag 18 has twopossible places to exit. One possibility includes exiting the solutionbag 18 from a port 163, entering a filter 166 and returning to theperitoneal cavity of the patient 16. Another possibility includesexiting the solution bag 18 at a port 165 and entering a nanofilter 164.The system 160 splits the dialysate fluid exiting the solution bag orcontainer 18.

The nanofilter 164 operates similar to the dialyzer 26 described above.The nanofilter 164 includes a membrane. The membrane of the nanofilter164 rejects most electrolytes, i.e., allows most of the electrolytes toreturn to the solution bag. The nanofilter 164, however, filters mostall of the urea and a small amount of sodium through the membrane andinto a sorbent system cartridge 32, which is similar to the sorbentcartridges described above. The sorbent cartridge 32 as described aboveabsorbs and the urea from the fluid that is able to permeate through themembrane of the nanofilter 164.

A plurality of pumps (not illustrated) are provided to individuallycirculate medical fluid or dialysate through the patient loop 12 and theregeneration loop 14. The pump or pumps that control the recirculationthrough the regeneration loop 14 are adapted to circulate theregenerating fluid at a different flow rate, i.e., much faster, than theflow rate of fluid pumped through the patient loop 12. It is believedthat by using this method, the need for a concentration bag such as theconcentration bags 44 described above would not be needed. Thus, itshould be appreciated that the system 160 is a closed loop system thatdoes not require any sort of make-up materials or any continuous sourceof outside fluid. The system 160 is therefore very adept at keeping airand other contaminants from entering the system.

In an alternative embodiment, the a reverse osmosis membrane or anelectrooxidation system replaces the sorbent cartridge 32. In thisalternative embodiment, a reconstitution or concentration bag, such asthe concentration bag 44, is likely to be necessary.

The regeneration loop 14 removes urea at a rate of approximately 50 to80%. The dialysate returns to the peritoneal cavity of the patient 16substantially free from uric acid, creatinine, small molecular weightorganics and middle molecules. Further, the nanofilter 164 can rejectcalcium magnesium at a rate of approximately 98% and glucose at a rateof approximately 80%. The permeate stream exiting the nanofilter 164includes urea, approximately 70% sodium chloride and approximately 20%glucose. It should be appreciated that the system 160 is useful forperforming continuous flow peritoneal dialysis.

Dual Loop System for Hemodialysis

Referring now to FIG. 9, a system 170 is illustrated. Each of theprevious systems 10, 100 and 110 of FIGS. 1, 3 and 4, respectively, canbe used for peritoneal dialysis or hemodialysis. However, each of thesystems described above has been primarily described and illustratedusing peritoneal dialysis, that is, the patient loop has beenillustrated using a dialysis solution. The system 170 illustrates thatthe dual lumen catheter or two single lumen catheters can be replaced bya hemodialysis needle 171, which connects to the arm (or other suitableportion) of the patient 16 to withdraw blood through the hemodialysisneedle 171.

The system 170 illustrates that the patient's blood flows through thepatient loop 12 while dialysate flows through the regeneration loop 14.The patient's blood flows along one side of the membrane 28 of thedialyzer 26, while the dialysate flows along the outside or other sideof the membrane 28 of the dialyzer 26. The waste components andultrafiltrate transfer from the patient's blood in the patient loop 12,through the membrane 28, into the dialysate in the regeneration loop 14.

The system 170 includes a fixed volume recirculating regeneration loop14 that dialyzes the patient fluid loop 12. A single pump 172 operatesto remove the ultrafiltrate from the patient 16 to the ultrafiltratecontainer 38. The pump 172 adds dialysis fluid from the dialysis bag 18or concentrate from the concentrate bag 44 to the regeneration loop 14.In an alternative embodiment, the concentrate can be metered into thedialysate of the regeneration loop 14 as a solid prior to or duringtherapy.

As an alternative to the capacitance volume sensing described above, thevolume of dialysate fluid flowing through the regeneration loop 14 canbe determined using an electronic balance 174 illustrated below thedialysate bags. The electronic balance 174 keeps track of the amount ofdialysate that is supplied to the system during a priming of the system.The electronic balance 174 also monitors any additional dialysate addedto the patient loop 12 during dialysis treatment. The electronic balance174 measures the amount of ultrafiltrate that is withdrawn from thesystem and the amount of the concentrate that is added from theconcentrate bag 44. In other alternative embodiments, any of the systemsdescribed herein can be sensed using other types of flowmeters ordevices employing Boyle's Law known to those of skill in the art.

The system 170 removes ultrafiltrate by opening a valve chamber andtransferring a known volume of the fluid into the ultrafiltrate bag 38.The removal of fluid creates a pressure differential across the membrane28 of the dialyzer 26, which causes fluid to filter through the dialyzermembrane 28 and into the regeneration circuit 14. Sterile dialysate froma supply bag 18 is infused into the patient circuit 12 as required.Concentrate from the concentrate bag 44 can also be infused into theregenerating circuit 14 as needed. Pressure sensors 176 monitor andcontrol the rate at which the system 170 draws ultrafiltrate into thecontainer 38.

Gas sensors 52 are used to prevent air from being delivered to thepatientl6. In an embodiment, a multi-analyte sensor 178 is employed tomonitor the concentration of electrolytes in the regenerated dialysateas well as the efficiency of the regeneration system in removing uremictoxins. The output of the multi-analyte sensor 178 controls the rate ofreconstitution from the concentrate bag 44, the efficiency of theregeneration system and can detect the presence of a leak in thedialyzer. A vent 180 vents air that becomes trapped in the system or CO2that is generated by the absorbent cartridge 32. In an alternativeembodiment, an automated valve that is provided integrally with theadsorbent cartridge 32 replaces the mechanical vent 180.

Although the system 170 is illustrated as a hemodialysis system, thesystem 170 is easily converted to a peritoneal dialysis system byplacing the catheter into the patient's peritoneal cavity and by runningdialysate through the patient loop 12 as opposed to the patient's blood.The ultrafiltrate bag 38, the dialysate container 18 and the concentratecontainer 44 each fluidly connect to the regeneration loop 14 and thepatient circuit is kept relatively simple. The system 170 is especiallyconducive for continuous flow of peritoneal dialysis, however, standardAPD and TIDAL therapies could be performed in the system 170.

Multi-Purpose Container

Referring now to FIG. 10, a combined absorbent cartridge, pump and valvesystem is placed into a single container, e.g., a canister, cartridge orcassette 190. The combination container 190 is illustrated as housingthe components specifically described in the system 170 of FIG. 9.However, the combination container 190 is adaptable to house thecomponents of any of the above-described systems, namely, the systems10, 100 and 110. The canister, cartridge or cassette is adaptable to bemade of any material such as plastic or metal. The container 190includes the adsorbent cartridge 32, which is configured as describedabove. Alternatively, the container includes the combination device 102that provides the adsorbent cartridge 32 and the gas separator 50.

The container 190 includes the pumps illustrated in FIG. 9 including thepump 172 that enables dialysate to be drawn from the dialysate bag 18 orconcentrate to be drawn from the concentrate bag 44. Additionally, thepump 172 enables ultrafiltrate to be drained into the bag 38. In anembodiment, the container 190 includes the multi-analyte sensor 178 andthe gas sensor 52, as described in the system 170 of FIG. 9. Thecontainer 190 also includes the mechanical or automated vent 180described in the system 170. Thus, the only devices external to thecontainer 190 are the dialysate bags and the hemodialysis needle 171that is inserted in the patient's arm or other extremity to performhemodialysis. Obviously, by the multi-lumen connector 20 and catheter 22can replace the needle 171 to perform peritoneal dialysis.

When the container 190 is provided in the form of a disposable cassette,the cassette 190, like the cassettes 120 and 140 of FIGS. 5 and 6, iscovered on at least one side with a flexible, e.g., plastic membrane(not illustrated). The disposable cassette 190 plugs into anon-disposable housing that provides the actuators for the variouspumps, e.g., the patient pumps 24, the dialysate pumps 30, theultrafiltrate pump 19 and the concentrate pump 46. The more expensivemechanical and electromechanical pieces of the flow components, e.g.,the pump actuators, are again kept and reused in the housing. Thesorbent cartridge 32 and the gas vent 180 can be disposable.

The above specification has been broken down into headings for purposesof readability, clarification and to promote the enablement of thepresent invention. The headings are in no way intended to limit thecombined teachings of the present invention. The features taught underany given heading are not limited to the embodiments disclosed under theheading. The present invention includes any combination of features fromthe disclosures under the different headings provided herein. Further,while the presently preferred embodiments have been illustrated anddescribed, numerous changes and modifications can be made withoutsignificantly departing from the spirit and scope of this invention.Therefore, the inventors intend that such changes and modifications arecovered by the appended claims.

The invention is claimed as follows:
 1. A peritoneal dialysis systemcomprising: a peritoneal dialysis machine including a pumping mechanism,and a sensor configured to measure a property of peritoneal dialysisfluid; and a disposable cassette operable with the peritoneal dialysismachine, the disposable cassette including a fluid source inlet foraccepting fluid from a fluid source, a fluid flow path in fluidcommunication with the fluid source inlet, the fluid flow path includinga pump chamber operable with the pumping mechanism to pump fluid throughthe fluid flow path, a concentrate inlet for fluidly communicatingconcentrate to the fluid flow path, and a sensor chamber located alongthe fluid flow path and operable with the sensor, wherein the sensor isconfigured to provide feedback to the peritoneal dialysis machine, andwherein the peritoneal dialysis machine is configured to use thefeedback to mix the concentrate for forming peritoneal dialysis fluid.